In general, methods for scanning an examination object with a CT system are well known. In this case, for example circular scans, sequential circular scans with feed or spiral scans are used. In the case of these scans, absorption data of the examination object is recorded by means of at least one x-ray source and at least one detector opposite it from different recording angles and the absorption data collected in this way is calculated by means of appropriate computing methods into sectional views through the examination object. Well known reconstruction methods are for example filtered back projection (FBP), in the case of which the projections are transferred to a Fourier chamber where a filtering is carried out and subsequently after the back transformation of the data, a back projection takes place on the sectional view plane.
As another method, mention can for example be made of the SMPR method (SMPR=segmented multiple plane reconstruction), in the case of which incomplete intermediate images are reconstructed from projection data over circular segments of smaller than 180°, which are subsequently combined into complete sectional views, while it must be noted that the total projection data used in this case must be complementary to 180° projection data or 360° projection data.
A disadvantage of these generally known calculation methods resides in that in the case of a moving examination object, or an at least partially moving examination object, a lack of definition due to movement may occur in the image, because there may be, during the time of a scanning process for the data required for an image, a local displacement of the examination object or a part of the examination object, so that the base data, that leads to an image, does not reflect the whole spatially identical situation of the examination object. This problem of a lack of definition due to movement occurs particularly strongly when cardio CT examinations are carried out on a patient, in which because of the movement of the heart, a strong lack of definition due to movement may occur in the heart area or for examinations in which relatively fast changes in the examination object are to be measured.